<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title></title>
 <style>
 *{
 margin:0;
 padding:0;
 list-style: none;
 }
 div{
 position: relative;
 width: 800px;
 height: 200px;
 border: 5px solid lightgreen;
 margin:10px auto;
 overflow: hidden;
 }
 div ul{
 position: absolute;
 left:0;
 top:0;
 }
 div ul li{
 width: 200px;
 height: 200px;
 float: left;
 }
 div ul li img{
 width:100%;
 height: 100%;
 }
 </style>
</head>
<body>
<div id="div1">
 <ul>
 <li><img src="http://www.qdfuns.com/misc.php?mod=attach&genre=editor&aid=b4251f00ef925cba01ed49ca117e14a7" alt=""/></li>
 <li><img src="http://www.qdfuns.com/misc.php?mod=attach&genre=editor&aid=d38403825519770211acbf49459ae7d7" alt=""/></li>
 <li><img src="http://www.qdfuns.com/misc.php?mod=attach&genre=editor&aid=53c83d39c62af65db998f4945bacaec2" alt=""/></li>
 <li><img src="http://www.qdfuns.com/misc.php?mod=attach&genre=editor&aid=5509f1a642644b40c8aa98c9e2c77a83" alt=""/></li>
 </ul>
</div>
<script>
 var oUl=document.getElementsByTagName('ul')[0];
 var lis=oUl.getElementsByTagName('li');
 oUl.innerHTML+=oUl.innerHTML;
 oUl.style.width=lis.length*lis[0].offsetWidth+'px';
 var left=null;
 var timer=setInterval(function(){
 left-=3;
 if(left<-oUl.offsetWidth/2){
 left=0;
 }
 oUl.style.left=left+'px'
 },10)
</script>
</body>
</html>